my ducks and chickens run together, but only my kaki campbell sleeps in the chicken house. my pekins sleep where they want to, usually in the barn with the goats.
the bad thing is they are messy, and will dirty up the water, if you have waterers, they will empty them quick and make a mess on the ground. We have a pool that we fill up for them to play in and bathe.
in the winter time we have a heated water bucket, but are building a platform for the chickens to get to the water where the ducks can't. we keep the heated water bucket outside so the ducks can get water.

Ducks and chicks don't really like each other. Ducks do spill and hog the water. They can live with just a little water but be prepared to refill it regularly. If you get a kiddy pond that will work. Ducks like to wander and will weed whatever grass gets wet. Their not fans of sleeping indoors.
Hens can hatch ducklings but sometimes freak when they 1st swim.

Our ducks and chickens share habitat, but the chickens choose to sleep on top of the rabbit cages (in the barn) and the ducks sleep on the floor. In their pen. We tried putting the chickens in the same pen, but since it has no cover, they just flew out and hopped on top of the rabbit cages. They have slept there ever since.

Ducks do not need a pond/ pool to be happy/ healthy. We do fill a kiddie pool for ours in good weather. During the winter, I only fill a small black rubber feed pan. It is easy to dump if frozen. It is not needed, but they like it. The chickens and ducks share an automatic poulty waterer that is rinsed and refilled once daily all year.

The chickens tend to stay close to the barn. The ducks wander all over the farm and come back to the barn occationally and at night. They do not flock together by choice, but don't mind each other either. They often eat out of the same pan at the same time with no problems.

katemary ~ Do your ducks have some sort of roofed nest on the floor? Or do they sleep directly on the floor and in the open? And do they come back to the barn on their own accord at night, or do you need to herd them?